Despite the difference in designation, the .476 Eley will readily interchange with the earlier .450 Adams and .455 Webley rounds (the latter in black powder Mark 1 and smokeless Marks 1 through 6), as well as the .455 Colt (a U.S. commercial brand for the same .455 Webley round, with slightly different ballistics), which all use the same .455 in (11.6mm) bullet, the distinction being in how the bullet diameter was measured.